The publication today of data on patient deaths during and after heart operations is a landmark step on the road towards a more open health system.

Alan Milburn, then health secretary, took the decision that patients should have the right to know about the results of their surgeons during a tense meeting at the Department of Health three years ago.

He had just finished reading the devastating report of an inquiry under Sir Ian Kennedy into the Bristol heart scandal. It recommended that patients should never again be kept in the dark about the clinical competence of their surgeons.

The Bristol Royal Infirmary experience was institutionally devastating for the NHS and a personal nightmare for the parents of many babies who died during heart operations by two surgeons who were not as proficient as surgeons elsewhere. The parents could not have known that and had no chance to seek help in other hospitals because of the lack of comparative data on death rates.

A surgeon and the trust's chief executive were struck off by the General Medical Council, and a second surgeon was suspended.

Sir Ian recommended that hospitals should publish their results for all to see. Mr Milburn decided that nothing less than individual death rates would do. He became determined to break down the walls of the secret garden of medical performance.

It was a step that was intended eventually to open the way to all sorts of clinical data, allowing patients and their GPs to make informed choices. It set the stage for the arguments about choice that are likely to dominate the health debate during the forthcoming general election.

The crunch came at the meeting in Mr Milburn's office in January 2002. He called in Bruce Keogh of the Society of Cardiothoracic Surgeons. A few years earlier, surgeons would never have contemplated allowing such sensitive data into the public domain, but the furore over Bristol had changed all that. Mr Keogh and other senior surgeons recognised the inevitability of public disclosure of each individual's death rates. It had already happened in America. Now it was the UK's turn.

Many surgeons were worried. Publication of mortality data would, they argued, cause more deaths. Patients would be scared into avoiding being treated by the ablest surgeons, who had the highest death rates because they took the hardest cases. The surgeons would react by shunning difficult work - refusing to treat the patients who had the most to gain from surgery.

That was what happened in New York, they said, when freedom of information laws forced the disclosure of mortality statistics.

Mr Milburn proposed a deal. Politically, he needed to get the data to the public. He would get the surgeons the funding to collect the information but they would have to deliver individual named surgeons' death rates.

It was a tough discussion, but they agreed to try to get individualised results, averaged over three years, to the public by 2004.

That year came and went without most surgeons' individual results seeing the light of day. A few trusts were proud enough of their own scores - and advanced enough in the science of risk measurement - to publish their own data on hospital websites. But some were barely trying.

At the end of last year, the society published information showing hospitals' aggregate results and gave an assurance that no individual surgeon departed too far from the average. The society has said it will be able to publish complete, validated, risk-adjusted results for all surgeons - but not for at least 18 months.

Yet still some trusts have put little effort into collecting the data. Some blame hospital managers who diverted the government money earmarked for setting up information systems into reducing waiting times.

The price for producing risk-adjusted data was about £50 per patient on an operation costing £8,500 or more. But with heavy pressure to cut waiting lists, every little helped.

Others thought lack of money might be an excuse advanced by surgeons who did not want even risk-adjusted data to come into the open.

Whatever the reason, John Reid, Mr Milburn's successor as health secretary, had little room for manoeuvre. Although committed to giving patients the right to make informed choices, he could not demand the publication of risk-adjusted data that did not exist in about a third of NHS trusts performing these operations.

That was where the debate stalled until the Freedom of Information Act came into force on January 1, giving citizens the right to apply for data held by public bodies, including hospitals. Richard Thomas, the information commissioner, forecast that this would lead to the publication of results for individual physicians. This would be controversial, but the patient's right to know was paramount, he said.

His comments paved the way for the Guardian's freedom of information request. The door on which Mr Milburn knocked three years ago has been opened a crack but the exploration of the secret garden has yet to begin.

· Additional reporting by Katy Heslop and Isabelle Chevallot and John Houston.